The present disclosure relates to gas turbine engines, and more particularly to Beta operation of a Counter-Rotating Open-Rotor (CROR).
A Counter-Rotating Open-Rotor (CROR) includes a gas turbine engine with counter-rotating un-ducted rotors outside a nacelle structure. Propfans are also known as ultra-high bypass (UHB) engines and, most recently, open rotor jet engines. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop.
CRORs may have particular challenges in terms of aerodynamics, aeroacoustics and structural dynamics as the forward and aft rotors are outside the nacelle structure and are positioned relatively close together which may result in rotor/rotor interactions.